1. Field of the Invention
The invention relates to a fuel inlet device, and more particularly to a fuel inlet device with a cap member for a fuel tank.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional fuel inlet device for a fuel tank in a vehicle (not shown) is shown to include a fuel inlet port 11 attached to the fuel tank through a fuel tube 10, and a cap member 12 adapted to be connected detachably to the fuel inlet port 11.
The fuel inlet port 11 is mounted to the vehicle, and includes a tube body 112 that defines therein a fuel-filling channel 110 in spatial communication with the fuel tube 10. The tube body 112 has an upper cap-mounting end 1121 formed with a circular central opening 111, and a lower connecting end 1122 connected to the fuel tube 10. The central opening 111 is defined by an inner annular wall 113 that is formed with two notches 114 opposite to each other in a radial direction of the tube body 112 (see FIG. 2) and in spatial communication with the opening 111 and the fuel-filling channel 110. The inner annular wall 113 has two abutting wall sections 115, each of which is disposed adjacent to a corresponding one of the notches 114, and two blocking wall sections 116, each of which is connected to a corresponding one of the abutting wall sections 115. Each of the abutting wall sections 115 has a bottom edge 1151 that extends gradually and downwardly toward a corresponding one of the blocking wall sections 116 connected therewith. Each of the blocking wall sections 116 has a downward projecting lower extension 1161.
The cap member 12 is adapted to be connected detachably to the fuel inlet port 11 to seal the fuel-filling channel 110. The cap member 12 includes an enlarged head portion 121, and a plug portion 122 connected to the head portion 121. The plug portion 122 has two radially extending semicircular protrusions 123 corresponding respectively to the notches 114 in the cap-mounting end 1121 of the tube body 112.
When the plug portion 122 is inserted into the fuel-filling channel 110 in the tube body 112 through the opening 111 in the cap-mounting end 1121 of the tube body 112, each of the notches 114 permits a corresponding one of the protrusions 123 to pass therethrough. In this case, the cap member 12 is at an open position. Thereafter, by operating the head portion 121 of the cap member 12, the cap member 12 is rotated relative to the fuel inlet port 11 in a first direction (A) to move from the open position to a closed position. During movement of the cap member 12 from the open position to the closed position, each of the protrusions 123 of the plug portion 122 of the cap member 12 abuts movably against and is guided by the bottom edge 1151 of a corresponding one of the abutting wall sections 115 of the inner annular wall 113 so as to move toward a corresponding one of the blocking wall sections 116 of the inner annular wall 113 such that the cap member 12 is connected tightly with the fuel inlet port 11, thereby sealing the fuel-filling channel 110. When the cap member 12 is at the closed position, each of the protrusions 123 of the plug portion 122 of the cap member 12 is blocked by the lower extension 1161 of the corresponding one of the blocking wall sections 116 of the inner annular wall 13. On the contrary, when the cap member 12 is rotated relative to the fuel inlet port 11 in a second direction (B) (see FIG. 2) opposite to the first direction (A) to move from the closed position to the open position, the cap member 12 can be detached from the fuel inlet port 11.
However, when the cap member 12 is moved to the closed position, the cap member 12 cannot be retained at the closed position due to lack of a positioning mechanism between the protrusion 123 and the abutting wall section 115. As a result, the cap member 12 may move away from the closed position in response to vibration of the vehicle such that tight connection between the fuel inlet port 11 and the cap member 12 cannot be ensured. On the other hand, when the cap member 12 is rotated in the second direction (B) from the closed position toward the open position to detach the cap member 12 from the fuel inlet port 11, excessive rotation of the cap member in the second direction (B) may occur, thereby resulting in misalignment of each of the protrusions 123 with the corresponding one of the notches 114, as shown in FIG. 2. Therefore, in order to detach the cap member 12 from the fuel inlet port 11, it is required to slightly rotate the cap member 12 in the first direction (A) again to align each of the protrusions 123 with the corresponding one of the notches 114, thereby resulting in inconvenience during detachment of the cap member 12.